The present invention relates to a heat transfer printing sheet, and, more specifically, to a heat transfer white-image-printing sheet having high hiding power, capable of producing images which are excellent in abrasion resistance.
A conventional heat transfer printing sheet of resin type which comprises a resin as the binder of the ink layer thereof is excellent in film-forming properties. However, when sensitivity and printability are taken into consideration, the ink layer of the printing sheet of this type cannot be formed by coating such an amount of an ink that is required to impart thereto sufficiently high hiding power. For this reason, a heat transfer printing sheet of wax type which comprises a wax as a main component of the binder of the ink layer thereof has been applied to a heat transfer white-image-printing sheet which is required to have hiding power. This is because when a wax is used as the binder, an increased amount of an ink can be coated to form the ink layer, an image with good edge definition can be obtained by heat transfer printing, and hiding power can be imparted to the printing sheet.
However, there has been such a problem in that although the wax-type heat transfer printing sheet can have hiding power higher than that of the resin-type one, an image produced by the wax-type one is poor in both abrasion resistance and heat resistance. An object of the present invention is to provide a heat transfer white-image-printing sheet having sufficiently high hiding power, capable of producing images which are excellent in abrasion resistance and heat resistance. We have made earnest studies in order to attain this object, and, as a result, found that a heat transfer white-image-printing sheet having sufficiently high hiding power and excellent printability, capable of producing images which are excellent in abrasion resistance and heat resistance can be obtained by providing a white ink layer comprising a resin as a main component of the binder thereof and fine hollow particles, or by successively providing a white ink layer comprising a resin as a main component of the binder thereof, and a layer comprising fine hollow particles.
A heat transfer printing sheet comprising fine hollow particles in a white ink layer has been conventionally disclosed in Japanese Laid-Open Patent Publication No. 147397/1990. Disclosed in this publication is such that since fine hollow particles whose wall is made from a shape memory resin expand to the original shape thereof by heat which is applied thereto when printing is conducted, an image can be printed even on paper having a rough surface without causing partial deletion or void. In contrast, in the present invention, fine hollow particles containing a gas therein are incorporated into a white ink layer to improve the hiding power of a heat transfer printing sheet. The present invention is thus substantially different from the above application in technical field.
An object of the present invention is to provide a heat transfer white-image-printing sheet having sufficiently high hiding power, being free from flaking, capable of providing a printed material which is excellent in both abrasion resistance and heat resistance.
The above object can be attained by a heat transfer white-image-printing sheet of the present invention, which comprises a substrate film, and a white ink layer comprising a resin as a main component of the binder thereof, a white pigment and fine hollow particles, provided on one surface of the substrate film; or comprises a substrate film, a white ink layer comprising a resin as a main component of the binder thereof and a white pigment, provided on one surface of the substrate film, and a heat-sensitive adhesion layer comprising fine hollow particles and a resin binder, provided on the white ink layer.